Transformer.



N. A. WOLCOTT & W. C. WOODLAND.

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' I i i NH I I w m4 Wadpqii W Waddle/ind llu UNITED STATES PATENTOFFICE.

NEWTON A. WOLCOTT AND WILLIAM G- WOODLAND, 0F WARREN, OHIO, ASSIGNOBS TOTHE PACKARD ELECTRIC COMPANY, OF WABBEN, OHIO,

A CORPORATION OF OHIO.

runsronuaa Specification of Letters Patent.

Patented Mar. 31, 1914..

A. Wontransformer construction to use what is that is, the.

known as reduced core section, portion of the iron which is directlyunder the winding is reduced in cross-section so as to allow a shortermean turn of copper.

In such transformers the laminations of the.

legs are of different widths, that is, they are composed. of centralsections and outer figure sub-' narrower sections, forming .a stantially+-shaped in cross-section, wherein one of the bars of the cross'may beconsidered as extending all the way across the figure. These legsections are connecte respectively by yoke sections in which heretoforeno account has been taken of the difference in the ratio of the magneticdensity between the portions of the yoke connecting the inner or moreextended leg sections and such leg sections, in the portions of the yokeconnecting the outer or narrower leg sections and such narrow legsections themselves. For example, while the ratio of magnetic densitybetween the portions of the yokes connecting the more extended orintermediate sections of the legs have been, we will say for example,approximately one, or unity, the ratio between the magnetic density ofthe portion of the yoke connecting the outer or more restricted legsections and such leg sections has borne no such equality, the

density of he more restricted leg sections both of V d nected by yokesections and the magnetic density y show up as increased core loss.

It is the primary'object of this invention to prevent such increase incore loss by more nearly equaliz ng themagnetic density in the variousparts of the yokes.

It 1s also the object of this invention to I provide a transformerhaving yokes in'evel'v part of the section of which yokes indivlduallyconsidered the magnetic densities are approximately equal, and havinglegs 1n every part 0 which legs individually considered the magneticdensity is approximately equal. In order to more fully describe ourinvenpanying drawings wherein,

Figure one form of transformer constructed in accordance with ourinvention. Fig. 2, a top plan view thereof. Fig. 3, an edge view inelevation of said transformer core.

In the accompanying drawings, I'designates the central or-wide legsections con- 3; 2 the narrower leg sectlons, and 4, yoke. sectionsconnecting the said narrower leg sections 2. These sections are as usualmade up of interleaved laminations of suitable magnetic metal, and the.number of laminations composing the the number of laminations of legsections 1. If, however, the laminations of yoke sections 4 equaled innumber those of the leg sections 2, as has been the custom, withoutmakin provision for equalizing the magnetic ensity of the parts of theyokes connecting with the different leg sections, it will be seen thatthe yoke sections 3 would carry a greater magnetic density than yoke"sections 4. In other words, the ratio of the magnetic density ofsections 1 to sections 3 would not be at all the same as the densityratio of sections 2 to sections 4, assuming the sections 4 to containthe same number of laminations as sections 2. For example, while themagnetic density in secwould be that the magnetic lines would cross inorder to fi'nd an easier path,

from the sections 3 into sections 4: of the yoke,

tion, reference will 'be had to the accom-- oke sect-ions 3, correspond,or nearly so,with

I by producing wasteful eddy currents which 1 1s a new in side elevationof" I tions 1 and 3 maybe approximately the same, the magnetic densityin sections 2 would -much greater than sections 4. The result? in theyoke,-

' one-half the plates,

and thereby set up eddy currents as ole scribed.

According to our invention, we omit enough of the plates in yokesections/l to make the net area thereof bear approximately the sameratio to that of leg sections 2 as the yoke sections 3 bear to legsections 1. The superficial area of the yoke sections may remainunchanged. As the net cross-sectional area of the yoke .sections 4 isusually over twice that of leg sections 2, the desired end may beattained by omitting about that is to say, every other plate ordinarilyrequired in making up the yoke sections 4 connecting the narrow legsections.

Our aim is to equalize the magnetic densi ties in all parts of the yokesconsidered separately and to equalize'the magnetic densities in allparts of the legs considered separ'ately so as to prevent the magneticlines of force from straying out of their proper paths.

By means of our invention, not only do We minimize the eddy-currents,resulting in specification in the presence of two lower core losses, butwe, at the same time, effect a saving in the material,- and these areitems of considerable importance in view of the urgent demand forlowercore losses,

netic core comprising parallel legs composed of sections of difi'erentwidths and yokes connecting said legs, the. yoke sections con nectingthe reduced widths of the legs being composed of a different number oflaminations from the yoke sections connecting the Widest portions of thelegs. I 1

In testimony whereof, we have signed this subscribing witnesses.

NEWTON A. WOLCOTT. WILLIAM C, WOODLAND.

Witnesses:

RQH. SNYDER, L. A. MARTIN.

